webadmin: using search backend to find Up server in cluster

To find whether there are any host in Up staus in a cluster,
SearchQuery is used with Status=Up and MaxCount 1 .

The code is refactored to use the new technique rather than
fetching the full host list of a cluster and iterating through
them.

Change-Id: Ib2ba449d2fa43d0c2e510ec4d0b51d3dc359b6ae
Signed-off-by: Kanagaraj M <kmayilsa@redhat.com>